The term "nude" can often refer to a few different looks/desired effects in the make up world. If can refer to giving the lips a more flesh toned appearance or just playing up the natural color of your lips, giving the look of not having on a super tell-tale lipstick/product on at all.

Try posting a photo here if yourself/lips in natural light so we can recommend some specific products to look into.

And for starters, to find lip colors that will look the most natural on you, pucker your lips and match your lipstick/balm/product to the color on the inner portion of your lips. This will give a more realistic match compared to just picking a shade that matches exactly to your lip color. From there you can deviate a little and find more flesh tones that still lay in line with the undertones of your shade so that way it remains complimentary without looking garish.